I think I left the ring in with mine, we just cut then burned out the old rubber, then used a vise to squeeze the new bushings in.
my st205 swapandour Beams swap
I used an air chisel both ways. I couldnt get them to fit into a hydraulic press, so i put a slab of metal on the bushing to even out the pressure and chiseled them in.
They ride nicely. Good luck and enjoy.